A. Field of Invention
The invention is directed to the field of elongate articles and methods for making them, such as baseball bats, oars, and any articles including tubing, such as bicycle frames, other bicycle components such as handlebars, bar ends, lugs, vehicle frames, handlebars and components for other vehicles such as motorcycles and all terrain vehicles, furniture, tennis rackets, golf clubs, ice and field hockey sticks, shoe inserts, wind turbine blades, propellers, pole vault poles, javelins, arrows, oars, paddles, gun stocks, archery bows, and other articles and their construction methods. More specifically, in one embodiment the invention is a baseball bat (xe2x80x9cbaseball batxe2x80x9d as used herein includes elongate articles of any type intended to be swung at a ball in the air, such as baseball and softball bats and children""s versions thereof) that includes a continuous fiber reinforced composite preform about which expanded, cured foam is molded or about which thermosetting or thermoplastic elastomer (including urethanes or other systems) are molded. The invention also includes a method for making the baseball bat and the other articles listed above. All of the information contained herein relates not only to bats and other articles used for or useful for striking a ball, other projectile or other objects, but also for each of the numerous articles listed herein as capable of taking advantage of the invented structure or being made from the invented process.
B. The Background Art
Various methods for manufacturing composites are known. Among these were U.S. Pat. No. 3,147,975 to Gruss et al., U.S. Pat. No. 3,258,511 to McGregor, U.S. Pat. No. 3,478,134 to Gruss et al., U.S. Pat. No. 3,619,436 to Gruss, U.S. Pat. No. 4,298,556 to Rutsch et al., U.S. Pat. No. 4,351,786 to Mueller, U.S. Pat. No. 4,614,627 to Curtis et al., U.S. Pat. No. 4,714,575 to Preston, and U.S. Pat. No. 5,042,968 to Fecto, each of which is hereby incorporated by reference in its entirety for the material disclosed therein. These patents relate to the manufacture of various composite items, including golf clubs, propeller blades, bowling pins and baseball bats, among other items. Also in the prior art, it was known that baseball bats could be made from wood, aluminum or titanium, and that oars and paddles could be made from wood, metal or a combination of them. None of these prior art patents disclose the use of a composite preform (such as a filament wound preform) as a structural component which is placed in a mold where foam is reaction injection molded around the preform to create the desired article. Nor do these prior art patents disclose such baseball bat that includes an aluminum knob pinned and bonded to its handle. Further the prior art patents do not disclose the various steps of the manufacturing process considered to be a part of the invention, all as described in detail below.
It is an object of the invention to provide a baseball bat which is durable. It is a feature of the invented bat in the preferred embodiment that a filament wound preform about which urethane foam or elastomer is molded provides the basic structure of the bat. It is a feature of the invented bat that in a more preferred embodiment, the invented bat is a filament wound preform with a toughened resin matrix.
It is an advantage of the invented bat that it will not break as will a wooden bat, no matter which portion of the bat strikes a ball. Further, the invented bat has been found to propel a ball to distances at least comparable to traditional wood and aluminum bats even when the ball is not hit with the xe2x80x9csweet spotxe2x80x9d of the bat. The invented bat has also been found to last with adequate performance for a greater number of hits than either wooden or aluminum bats.
It is an object of the invention to provide a baseball bat which is safe to use. As mentioned above, the structure of the bat effectively resists breakage and the potential for injury that accompanies such breakage. Further, however, it is a characteristic of the preferred materials of the invention, such as the composite preform and the moldable material of the preferred embodiment, to inherently absorb shock and vibration without the objectional metallic sound and accompanying vibration of prior art aluminum bats. Consequently, when a player strikes a ball with the invented bat, whether or not the ball is struck on the sweet spot of the bat, the bat will not exhibit substantial vibration of its handle (resulting in a xe2x80x9cstingingxe2x80x9d sensation to the user) which in prior art bats has the potential to injure the hands or arms of the player using the bat.
It is an object of the invention to provide a bat which is consistent. It is a feature of the invention that the materials from which the invented bat is made are not subject to substantial change or degradation over time or when exposed to various weather conditions, including varying humidity and temperature, in contrast to prior art wood bats and to a lesser extent prior art metal bats. Also, in contrast with wood bats which depend on the material wood and its accompanying irregularities, each of the invented bats that is produced can be made identical to each other, so players can readily switch bats without noticing performance differences. It is a further feature of the invention that the bat can be held and swung in any orientation to strike a ball without negative effect, in contrast to wood bats. It is a further feature of the invention that the sweet spot of the bat is typically quite large due to the internal consistency of the materials used. Consequently, it is an advantage of the invented bat that a player may hold the invented bat in any orientation and use it in any weather conditions over a long period of time with no variation in the performance of the bat.
It is an object of the invention to provide a bat which is price competitive while offering desirable performance characteristics. As a result of the preform and moldable material, which in the preferred embodiment are price competitive compared to other composite materials, and the manufacturing process which can be automated and is not labor intensive, very competitively priced but high quality bats can be produced.
It is an object of the invention to provide an elongate object which has a high strength to weight ratio. By using a filament wound or other composite preform, combined with a molded exterior, a finished article is produced which is inherently strong due to the materials and structure of the preform and due to a reinforcing effect of the molded materials about the preform. The materials used in the preferred embodiment have relatively low specific gravities in comparison to other intermediate and high strength materials, so the result is a very strong yet light finished article.
It is an object of the invention to provide safe, durable, consistent and competitively priced paddles, oars, bicycle frames, bicycle handlebars, other bicycle components, field and ice hockey sticks, shoe inserts, golf clubs, tennis rackets, furniture, gun stocks, wind turbine blades, propellers, generic tubing and other articles useful for a variety of purposes. Because all of these articles when constructed with the invented structure or according to the invented method incorporate the same advantageous features of the bat (as discussed above), each such article will also achieve these objects of invention.
It is an object of the invention to provide a manufacturing process that yields a durable, safe, consistent and inexpensive high performance articles, including baseball bats, oars, paddles, bicycle components, generic tubing, and other articles. Because the manufacturing process yields articles having the advantageous structure and characteristics discussed above, these objects are achieved by the manufacturing process.
Additional objects, features and advantages of the invention will become apparent to persons of ordinary skill in the art upon reading the remainder of the specification and upon referring to the attached Figures.